The present invention refers to an electrical connector for coaxial cables with helically corrugated outer conductor and smooth or helically corrugated inner conductor.
In general, a connector for attachment to the corrugated outer conductor of a coaxial cable includes a connector housing with a bore formed therein for receiving a cable end, and a corrugated nut which is threaded on the outer cable conductor and securely tightened to the connector housing to establish a contact. The connection of the central inner connector conductor with a tubular inner corrugated cable conductor can be created via a central screw fastener which engages a plug received in the end section of the inner cable conductor and having an outer circumference substantially complementing the helical corrugation of the inner cable conductor
Connectors are known, e.g. from U.S. Pat. No. 3,291,895, in which the corrugated outer conductor of the coaxial cable is solely contacted with the connector housing by pressing the end face of the outer conductor against an annular surface in the bore of the connector housing when tightening the corrugated nut for engagement with the connector housing. Since materials used for the outer cable conductor include primarily copper alloys or aluminum alloys which tend to a plastic deformation in particular when subjecting the cable to mechanical stress, this type of contact making will progressively deteriorate and impair the quality of contact making in particular when large armatures are concerned.
For this reason, connectors have long been used which are designed in such a manner that the outer cable conductor is provided with a front edge which is flanged outwardly at a right angle or at least flared and securely clamped between respective ring surfaces or conical surfaces in the connector housing. One clamping surface may be formed on a tension ring in the connector housing or in a bore thereof while the other clamping surface may be provided directly on the corrugated nut or on a separate compressor. The clamping action can be accomplished by securing the corrugated nut to the connector housing. Alternatively, the clamping action may be created through provision of a separate clamping or receiving sleeve which acts upon the corrugated nut and is screwed to the connector housing or secured via screw fasteners. Connectors of this type are disclosed e.g. in German publications DE-OS 21 27 927, DE-OS 35 22 736 and DE-OS 42 02 813. Despite realizing good to very good electric properties, the assembly of such connectors is very complicated, in particular when considering the required flaning through special flooring machines and subsequent aligning of the outer conductor end.
European Pat. No. EP 0 517 034 A2 discloses a connector in which the inner connector conductor is essentially of two-part construction, with one part being securely supported by a conventional insulator and including in direction of the cable a sleeve with several axial slots. The other part of the inner connector conductor includes the central screw fastener with a cylindrical head which is overlapped by the slotted sleeve of the one part of the inner connector conductor after assembly. The attachment of the connector to the coaxial cable requires a suitable preparation of the coaxial cable end for allowing a complete insertion of the plug into the inner cable conductor. Subsequently, the central screw fastener is threaded into the plug until a collar provided on the screw fastener between the shank and the head is securely clamped against the end face of the inner cable conductor, with the collar of the screw fastener including two key areas. A connector of this type has the drawback that on the one hand the plug must be threaded into the inner cable conductor and on the other hand after being attached must be secured non-rotatably in order to avoid a subsequent turning when the central screw fastener is screwed in. Only after this preassembly can the connector housing, generally a plug-type connector head, be mounted to the end of the coaxial cable.